Analysis of 2005 Dahuieh (Zarand) aftershock sequences in Kerman province, southeast Iran

In this study, the 2005 Dahuieh (Zarand) locally recorded aftershock sequence has been analyzed. Having the distribution of aftershocks and the source extension, a W-E trending near vertical faulting with an extension of about 15-20 km could be estimated. The rupture causing the powerful Dahuieh earthquake apparently initiated in the modified epicentric area and propagated unilaterally towards the west. The cross section of aftershocks perpendicular to the fault suggests that the aftershocks had a depth range about 20 km, indicating that the seismic activity took place within the upper crust and the seismogenic layer, in this region, which had a thickness not greater than 20 km. The focal mechanism of the main shock and right lateral motion of the Kuh-Bannan fault suggested that the earthquake fault must be reverse and the northern block acted as a hanging wall during the source process of the main shock. The epicenteral distribution of aftershocks showed a lack of activity that was interpreted as the modified location of the main shock. Our results are in agreement with waveform modeling. The time frequency pattern of the aftershock decay followed the Kisslinger stretched exponential descending formula.